The present invention relates in general to friction shock-absorbing apparatus and, more particularly, the present invention relates to a collar member which provides strength to and friction surfaces for such friction shock-absorbing apparatus and to a method of assembling such friction shock-absorbing apparatus utilizing such collar member.
Although not to be limited thereby, the present invention will be described hereinafter as a railway draft gear assembly, which represents one use for such friction shock-absorbing apparatus.
Prior to the present invention, draft gear assemblies have been used for many years to absorb shock encountered in operating railway vehicles. One example of such draft gear is shown in U.S. Pat. No. 2,463,373, the teaching of which is incorporated herein by reference. This draft gear uses a casting or forged housing open at the front end and closed at its rear end. The casing is of hexagonal transverse cross-section with the walls thereof thickened at its open end. The thickened wall portion provide friction surfaces of V-shaped transverse cross-section. At the open end, the casing is provided with stop lugs at the corners of the casing adjacent the V-shaped surfaces.
A wedge having wedge faces of V-shaped transverse cross-section includes outwardly-projecting radial lugs engaged by the stop lugs.
Three friction shoes having a V-shaped friction surface are interposed between the wedge faces and the casing friction surfaces. The inner end of each shoe has a flat abutment face on which a spring resistance bears. The forward end of each shoe is beveled at opposite sides of its longitudinal center to provide clearance for the wedge block lugs and guide the same in position in back of the cooperating casing lugs.
In assembling the mechanism, the casing is positioned upright and the spring resistance is placed therein. The shoes are then placed on top of the spring. Next, the wedge block is entered between the shoes. The shoes are forced inwardly of the casing against the resistance of the spring until the wedge lugs pass inwardly beyond the casing lugs, thereby freeing the wedge for rotation. Turning of the wedge in a contraclockwise direction engages the wedge lugs in back of the casing lugs, thereby locking the wedge against outward movement.
As can be seen from the above description, such prior art draft gear is rather complex, heavy, and costly to manufacture. These characteristics are typical of prior art type friction draft gear.